1. Field of the Invention
The field of the invention is position determining methods and apparatus utilized in determining the position of a movable element mounted for movement on a path.
2. Description of the Prior Art
Heretofore various position determining devices have been proposed. Many of these devices include comparing circuits. Also numerous comparing circuits have been proposed for a variety of applications.
The previously proposed position determining devices usually have required a reference or starting point in order to determine the absolute position of a movable element on a path. Also such devices have not always been able to determine the direction of movement of the movable element. Examples of previously proposed position determining devices and electronic comparing circuits are disclosed in the following United States Patents:
2,765,459 PA1 2,808,650 PA1 2,885,613 PA1 3,064,889 PA1 3,268,713 PA1 3,582,924
As will be described in greater detail hereinafter the position determining method and apparatus of the present invention differ from the previously proposed methods and devices by providing for the determination of the absolute position of a movable element on a path without reference to a starting or reference point on the path. Also the method and apparatus can determine the direction of movement of the movable element. Additionally, the method includes the steps of and the apparatus includes circuitry for detecting whenever there is an error in the determination of the position of the movable element on the path and for making, thereafter, a new and correct determination of the position of the movable element on the path.